Fig. 9

Histological findings at 1 month following the instillation and the evaluation of lung lesions. A–C and D–F show HE staining and MT staining images, respectively, at 1 month after the instillation of 0.2 mg or 1.0 mg-CL-PAA. Red and black arrow heads, and black arrows indicate neutrophils and macrophages, and collagen deposition, in the alveolar space or alveolar septa, respectively. Histological findings of NiO nanoparticles and CeO₂ nanoparticles were shown in our previous report [16, 17]. G shows the inflammatory cell infiltration score in the 0.2 mg or 1.0 mg CL-PAA, NiO nanoparticles, or CeO₂ nanoparticles-exposed lungs at 1 month after the instillation. The inflammatory cell infiltration was observed in dose dependent manner, and more prominent compared to the NiO nanoparticles or CeO₂ nanoparticle. H shows the Ashcroft score in the 1.0 mg CL-PAA, NiO nanoparticles and CeO₂ nanoparticles-exposed lungs at 1 month and 3 months after the instillation. Although pulmonary fibrosis induced was persisted in each exposed group during 1 month to 3 months after the instillation, it was more severe by CL-PAA than by NiO nanoparticles and CeO2 nanoparticles. The Ashcroft score of each control group was all zero. Data are presented as mean ± SE (**p < 0.01, ^††p < 0.01, ^§p < 0.05, ^‡‡p < 0.01, ^¶p < 0.05, ^||||p < 0.01, *indicates that there is a significant difference in scores between the two groups. N.S. means no significance.) n-NiO and n-CeO₂ indicate that NiO nanoparticles and CeO₂ nanoparticles, respectively. One-way analysis of variance (ANOVA) followed by Turkey's test was used to appropriately to detect individual difference among the exposed groups